https://blog.turboawesome.win/tags/gc/ Recent content in Gc on Bits, Trades & Systems Hugo en-us Tue, 18 Apr 2017 09:11:00 +0000 https://blog.turboawesome.win/2017/04/reading-gc-logs-like-a-detective/ Tue, 18 Apr 2017 09:11:00 +0000 https://blog.turboawesome.win/2017/04/reading-gc-logs-like-a-detective/ GC logs are the most information-dense diagnostic output the JVM produces, and most engineers never learn to read them properly. A guide to interpreting G1GC logs and using them to diagnose real production problems. https://blog.turboawesome.win/2016/08/heap-dumps-and-flight-recorder-diagnosing-jvm-memory-problems-in-production/ Wed, 24 Aug 2016 14:55:00 +0000 https://blog.turboawesome.win/2016/08/heap-dumps-and-flight-recorder-diagnosing-jvm-memory-problems-in-production/ Heap dumps and Java Flight Recorder are the two tools that diagnose production JVM memory problems. Understanding how to capture them without killing the service, and how to read what they tell you, is a gap in most JVM engineers' toolkits. https://blog.turboawesome.win/2015/10/zgc-and-shenandoah-what-low-pause-gc-means-for-trading-systems/ Thu, 01 Oct 2015 09:44:00 +0000 https://blog.turboawesome.win/2015/10/zgc-and-shenandoah-what-low-pause-gc-means-for-trading-systems/ In 2015 the JVM GC landscape was about to change significantly. ZGC and Shenandoah were in development, promising sub-millisecond GC pauses regardless of heap size. Here's what the previews looked like and what they meant for latency-sensitive Java. https://blog.turboawesome.win/2015/05/understanding-safepoints-the-jvm-pauses-nobody-talks-about/ Wed, 27 May 2015 14:38:00 +0000 https://blog.turboawesome.win/2015/05/understanding-safepoints-the-jvm-pauses-nobody-talks-about/ GC pauses get all the attention, but safepoints are a broader category of JVM stop-the-world events that affect latency in ways GC tuning can't fix. https://blog.turboawesome.win/2014/08/choosing-a-gc-collector-for-low-latency-java-a-practical-comparison/ Wed, 06 Aug 2014 10:18:00 +0000 https://blog.turboawesome.win/2014/08/choosing-a-gc-collector-for-low-latency-java-a-practical-comparison/ CMS vs G1 vs parallel GC vs no-GC strategies. The tradeoffs as they actually played out in a latency-sensitive financial application, with real numbers. https://blog.turboawesome.win/2014/04/off-heap-memory-in-java-sun.misc.unsafe-and-chronicle-map/ Wed, 02 Apr 2014 10:17:00 +0000 https://blog.turboawesome.win/2014/04/off-heap-memory-in-java-sun.misc.unsafe-and-chronicle-map/ The Java heap is GC'd. Off-heap memory is not. For large data structures that don't benefit from GC management and do benefit from predictable latency, off-heap allocation via Unsafe and Chronicle Map is the right tool — if you respect its dangers. https://blog.turboawesome.win/2012/11/stop-the-world-gc-pauses-killed-our-sla-and-what-we-did-about-it/ Tue, 13 Nov 2012 11:08:00 +0000 https://blog.turboawesome.win/2012/11/stop-the-world-gc-pauses-killed-our-sla-and-what-we-did-about-it/ How garbage collection pauses blew our latency SLA during peak market hours, and the three-phase approach we used to get it under control.